1 | /* |
2 | * COPYRIGHT (c) 2008 |
3 | * The Regents of the University of Michigan |
4 | * ALL RIGHTS RESERVED |
5 | * |
6 | * Permission is granted to use, copy, create derivative works |
7 | * and redistribute this software and such derivative works |
8 | * for any purpose, so long as the name of The University of |
9 | * Michigan is not used in any advertising or publicity |
10 | * pertaining to the use of distribution of this software |
11 | * without specific, written prior authorization. If the |
12 | * above copyright notice or any other identification of the |
13 | * University of Michigan is included in any copy of any |
14 | * portion of this software, then the disclaimer below must |
15 | * also be included. |
16 | * |
17 | * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION |
18 | * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY |
19 | * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF |
20 | * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING |
21 | * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF |
22 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE |
23 | * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE |
24 | * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR |
25 | * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING |
26 | * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN |
27 | * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF |
28 | * SUCH DAMAGES. |
29 | */ |
30 | |
31 | #include <crypto/skcipher.h> |
32 | #include <linux/types.h> |
33 | #include <linux/jiffies.h> |
34 | #include <linux/sunrpc/gss_krb5.h> |
35 | #include <linux/pagemap.h> |
36 | |
37 | #include "gss_krb5_internal.h" |
38 | |
39 | #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) |
40 | # define RPCDBG_FACILITY RPCDBG_AUTH |
41 | #endif |
42 | |
43 | /* |
44 | * We can shift data by up to LOCAL_BUF_LEN bytes in a pass. If we need |
45 | * to do more than that, we shift repeatedly. Kevin Coffman reports |
46 | * seeing 28 bytes as the value used by Microsoft clients and servers |
47 | * with AES, so this constant is chosen to allow handling 28 in one pass |
48 | * without using too much stack space. |
49 | * |
50 | * If that proves to a problem perhaps we could use a more clever |
51 | * algorithm. |
52 | */ |
53 | #define LOCAL_BUF_LEN 32u |
54 | |
55 | static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift) |
56 | { |
57 | char head[LOCAL_BUF_LEN]; |
58 | char tmp[LOCAL_BUF_LEN]; |
59 | unsigned int this_len, i; |
60 | |
61 | BUG_ON(shift > LOCAL_BUF_LEN); |
62 | |
63 | read_bytes_from_xdr_buf(buf, 0, head, shift); |
64 | for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) { |
65 | this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift)); |
66 | read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len); |
67 | write_bytes_to_xdr_buf(buf, i, tmp, this_len); |
68 | } |
69 | write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift); |
70 | } |
71 | |
72 | static void _rotate_left(struct xdr_buf *buf, unsigned int shift) |
73 | { |
74 | int shifted = 0; |
75 | int this_shift; |
76 | |
77 | shift %= buf->len; |
78 | while (shifted < shift) { |
79 | this_shift = min(shift - shifted, LOCAL_BUF_LEN); |
80 | rotate_buf_a_little(buf, shift: this_shift); |
81 | shifted += this_shift; |
82 | } |
83 | } |
84 | |
85 | static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift) |
86 | { |
87 | struct xdr_buf subbuf; |
88 | |
89 | xdr_buf_subsegment(buf, &subbuf, base, buf->len - base); |
90 | _rotate_left(buf: &subbuf, shift); |
91 | } |
92 | |
93 | u32 |
94 | gss_krb5_wrap_v2(struct krb5_ctx *kctx, int offset, |
95 | struct xdr_buf *buf, struct page **pages) |
96 | { |
97 | u8 *ptr; |
98 | time64_t now; |
99 | u8 flags = 0x00; |
100 | __be16 *be16ptr; |
101 | __be64 *be64ptr; |
102 | u32 err; |
103 | |
104 | dprintk("RPC: %s\n" , __func__); |
105 | |
106 | /* make room for gss token header */ |
107 | if (xdr_extend_head(buf, base: offset, GSS_KRB5_TOK_HDR_LEN)) |
108 | return GSS_S_FAILURE; |
109 | |
110 | /* construct gss token header */ |
111 | ptr = buf->head[0].iov_base + offset; |
112 | *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff); |
113 | *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff); |
114 | |
115 | if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0) |
116 | flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR; |
117 | if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0) |
118 | flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY; |
119 | /* We always do confidentiality in wrap tokens */ |
120 | flags |= KG2_TOKEN_FLAG_SEALED; |
121 | |
122 | *ptr++ = flags; |
123 | *ptr++ = 0xff; |
124 | be16ptr = (__be16 *)ptr; |
125 | |
126 | *be16ptr++ = 0; |
127 | /* "inner" token header always uses 0 for RRC */ |
128 | *be16ptr++ = 0; |
129 | |
130 | be64ptr = (__be64 *)be16ptr; |
131 | *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64)); |
132 | |
133 | err = (*kctx->gk5e->encrypt)(kctx, offset, buf, pages); |
134 | if (err) |
135 | return err; |
136 | |
137 | now = ktime_get_real_seconds(); |
138 | return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; |
139 | } |
140 | |
141 | u32 |
142 | gss_krb5_unwrap_v2(struct krb5_ctx *kctx, int offset, int len, |
143 | struct xdr_buf *buf, unsigned int *slack, |
144 | unsigned int *align) |
145 | { |
146 | time64_t now; |
147 | u8 *ptr; |
148 | u8 flags = 0x00; |
149 | u16 ec, rrc; |
150 | int err; |
151 | u32 headskip, tailskip; |
152 | u8 decrypted_hdr[GSS_KRB5_TOK_HDR_LEN]; |
153 | unsigned int movelen; |
154 | |
155 | |
156 | dprintk("RPC: %s\n" , __func__); |
157 | |
158 | ptr = buf->head[0].iov_base + offset; |
159 | |
160 | if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP) |
161 | return GSS_S_DEFECTIVE_TOKEN; |
162 | |
163 | flags = ptr[2]; |
164 | if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) || |
165 | (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR))) |
166 | return GSS_S_BAD_SIG; |
167 | |
168 | if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) { |
169 | dprintk("%s: token missing expected sealed flag\n" , __func__); |
170 | return GSS_S_DEFECTIVE_TOKEN; |
171 | } |
172 | |
173 | if (ptr[3] != 0xff) |
174 | return GSS_S_DEFECTIVE_TOKEN; |
175 | |
176 | ec = be16_to_cpup(p: (__be16 *)(ptr + 4)); |
177 | rrc = be16_to_cpup(p: (__be16 *)(ptr + 6)); |
178 | |
179 | /* |
180 | * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss |
181 | * doesn't want it checked; see page 6 of rfc 2203. |
182 | */ |
183 | |
184 | if (rrc != 0) |
185 | rotate_left(base: offset + 16, buf, shift: rrc); |
186 | |
187 | err = (*kctx->gk5e->decrypt)(kctx, offset, len, buf, |
188 | &headskip, &tailskip); |
189 | if (err) |
190 | return GSS_S_FAILURE; |
191 | |
192 | /* |
193 | * Retrieve the decrypted gss token header and verify |
194 | * it against the original |
195 | */ |
196 | err = read_bytes_from_xdr_buf(buf, |
197 | len - GSS_KRB5_TOK_HDR_LEN - tailskip, |
198 | decrypted_hdr, GSS_KRB5_TOK_HDR_LEN); |
199 | if (err) { |
200 | dprintk("%s: error %u getting decrypted_hdr\n" , __func__, err); |
201 | return GSS_S_FAILURE; |
202 | } |
203 | if (memcmp(p: ptr, q: decrypted_hdr, size: 6) |
204 | || memcmp(p: ptr + 8, q: decrypted_hdr + 8, size: 8)) { |
205 | dprintk("%s: token hdr, plaintext hdr mismatch!\n" , __func__); |
206 | return GSS_S_FAILURE; |
207 | } |
208 | |
209 | /* do sequencing checks */ |
210 | |
211 | /* it got through unscathed. Make sure the context is unexpired */ |
212 | now = ktime_get_real_seconds(); |
213 | if (now > kctx->endtime) |
214 | return GSS_S_CONTEXT_EXPIRED; |
215 | |
216 | /* |
217 | * Move the head data back to the right position in xdr_buf. |
218 | * We ignore any "ec" data since it might be in the head or |
219 | * the tail, and we really don't need to deal with it. |
220 | * Note that buf->head[0].iov_len may indicate the available |
221 | * head buffer space rather than that actually occupied. |
222 | */ |
223 | movelen = min_t(unsigned int, buf->head[0].iov_len, len); |
224 | movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip; |
225 | BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen > |
226 | buf->head[0].iov_len); |
227 | memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); |
228 | buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; |
229 | buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip); |
230 | |
231 | /* Trim off the trailing "extra count" and checksum blob */ |
232 | xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); |
233 | |
234 | *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip); |
235 | *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip); |
236 | return GSS_S_COMPLETE; |
237 | } |
238 | |